Influence of high intensity ultrasound on milk fat

Ultrazvuk visoke snage i niskih frekvencija smatra se ultrazvukom visokog intenziteta jer uzrokuje pojavu kavitacije te ima primjenu u prehrambenoj industriji. Fenomen kavitacije omogućuje učinkovitu homogenizaciju mlijeka smanjujući promjer globula masti na manje od 1μm, a ultrazvuk u kombinaciji s toplinom i/ili tlakom je učinkovit u postupcima konzerviranja mlijeka. Ispitivanjem sastava masnih kiselina ultrazvukom obrađenog mlijeka uočen je pad udjela nezasićenih masnih kiselina, a uz povišeni peroksidni i anisidinski broj to upućuje na oksidativne promjene na lipidima. Sekundarni produkti oksidacije lipida uključuju aldehide, karboksilne kiseline, alkohole i kratkolančane ugljikovodike koji negativno utječu na okus mlijeka. Podaci iz drugih istraživanja upućuju na primjetne promjene okusa pri tretmanu dužem od dvije minute. Optimizacijom procesnih uvjeta radi minimiziranja negativnog utjecaja, ultrazvuk se nameće kao alternativa konvencionalnim postupcima u proizvodnji mlijeka i mliječnih proizvoda.High power and low frequency ultrasound is considered to be of high intensity because it causes cavitation and has applications in the food industry. The phenomenon of cavitation enables efficient homogenization of milk by reducing the diameter of the fat globules to less than 1μm and ultrasound in combination with heat and / or pressure is effective in preservation procedures of milk. By examining the composition of fatty acids in ultrasound treated milk, decline of unsaturated fatty acids was observed. Considering high peroxide and anisidine value, that points to oxidative changes in lipids. Secondary products of lipid oxidation include aldehydes, carboxylic acids, alcohols and short chain hydrocarbons that negatively affect the taste of milk. Data from other studies indicate a noticeable change in taste at treatment of more than two minutes. By optimizing process conditions to minimize negative effects, ultrasound is emerging as an alternative to conventional methods in the production of milk and dairy products